Adaptive buffer partitioning method for shared buffer switch and switch therefor

Abstract

A method for adaptively partitioning a buffer in a shared buffer switch is provided. The buffer partitioning method for a shared buffer switch which has a plurality of input ports, a plurality of output ports, and a shared buffer, the method for determining whether or not to store a cell, which is newly received through one of the input ports, in the shared buffer comprises the steps of (a) determining a buffer area of the shared buffer in which the newly received cell is stored; (b) determining a cell discard threshold with respect to the total number of cells stored in the shared buffer and the changing rate, with respect to time, of the total number of the cells; and (c) determining whether or not to store the newly received cell in the shared buffer, by comparing the number of cells stored in the buffer area in which the newly received cell is to be stored, with the cell discard threshold. In the method, using a cell discard threshold which is determined with respect to the total number of cells stored in a shared buffer and the changing rate of the total number of cells, it is determined whether or not to store a newly received cell. Therefore, the shared buffer switch adaptively handles changes in inflowing traffic volume and changes in outflowing cell traffic volume such that cell loss due to cell discard is effectively prevented.

Description

BACKGROUND OF THE INVENTION[0001]1. Field of the Invention[0002]The present invention relates to a shared buffer switch, and more particularly, to a buffer partitioning method for a shared buffer switch and a shared buffer switch which is used in the method.[0003]2. Description of the Related Art[0004]A network which transfers data among communications apparatuses includes a plurality of switching nodes. Shared buffer switches are widely used as switching nodes. Since the size of a shared buffer is limited, unless the shared buffer is partitioned appropriately with respect to the traffic volume of inflowing cells and the operating environments, the performance of the switch will be degraded. That is, under the same hardware environments, the cell loss ratio and buffer utilization ratio will differ according to a shared buffer partitioning method.[0005]Among prior art methods for efficiently partitioning a shared buffer, there are a virtual partitioning method, a dynamic threshold me...

AI Technical Summary

Problems solved by technology

Since the size of a shared buffer is limited, unless the shared buffer is partitioned appropriately with respect to the traffic volume of inflowing cells and the operating environments, the performance of the switch will be degraded.

Since the virtual partitioning method uses a fixed threshold for each output port, it is difficult for the method to be actively adapted to the external condition changes such as backpressure.

In addition, since it is difficult to predetermine thresholds for traffic whose variables cannot be specified in advance such as Unspecified Bit Rate (UBR) traffic, the method cannot be applied to such traffics.

Furthermore, since the method uses only the total number of the cells as the criterion, it is difficult for the method to be swiftly adapted to traffic changes and external conditions change.

For example, even when an inflowing traffic is small for one output port, since the allocated buffer areas have same sizes for all output ports, the buffer area allocated to the output port of small inflowing traffic has many wasted parts.

Therefore, even when many empty spaces are available in a shared buffer, cell loss may occur, and the method cannot be promptly adapted to traffic changes and external conditions change.

The dynamic partitioning method uses interpolation to prevent a sudden change in a threshold, so the method needs complicated hardware for a plurality of multiplication and division, and high speed operation may be difficult.

Also, since a cell discard threshold is determined only by the total number of cells, the method cannot be adapted to traffic changes and external environment changes.

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